setbuf()
QNX SDP8.0C Library ReferenceAPIDeveloper
Associate a buffer with a stream
Synopsis:
#include <stdio.h>
void setbuf( FILE *fp,
char *buffer );
Arguments:
- fp
- The stream that you want to associate with a buffer.
- buffer
- NULL, or a pointer to the buffer; see below.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The setbuf() function associates the supplied buffer with the stream specified by fp. If you want to call setbuf(), you must call it after opening the stream, but before doing any reading, writing, or seeking.
If buffer is NULL, all input/output for the stream is completely unbuffered. If buffer isn't NULL, then it must point to an array that's at least BUFSIZ characters long, and all input/output is fully buffered.
Note:
- The setbuf() function doesn't have a way to notify you if an error occurred; you should use setvbuf() instead.
- As a QNX OS extension, you can use the
STDIO_DEFAULT_BUFSIZE environment variable to override
BUFSIZ as the default buffer size for stream I/O. The value of
STDIO_DEFAULT_BUFSIZE must be greater than that of
BUFSIZ. For more information, see
Adjusting the buffer size
in the entry for fopen().
Examples:
#include <stdio.h>
#include <stdlib.h>
int main( void )
{
char *buffer;
FILE *fp;
buffer = (char *)malloc( BUFSIZ );
if( buffer == NULL ) {
return EXIT_FAILURE;
}
fp = fopen( "some_file", "r" );
setbuf( fp, buffer );
/* . */
/* . */
/* . */
fclose( fp );
free( buffer );
return EXIT_SUCCESS;
}
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Signal handler | No |
| Thread | Yes |
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